阅读说明：本技术 一种Q500qENH免涂装桥梁钢用药芯焊丝及其制备方法 (Flux-cored wire for Q500qENH coating-free bridge steel and preparation method thereof ) 是由 郭栖利 官忠波 张克静 曾志超 蒋勇 张晓柏 于 2019-11-13 设计创作，主要内容包括：本发明公开了一种Q500qENH免涂装桥梁钢用药芯焊丝及其制备方法,由钢制外皮和药粉芯组成,该药粉芯包括以下组成成分：金红石3.5-5重量份、硅铁粉2-4重量份、钛铁粉0.3-0.5重量份、氟化物0.2-0.3重量份、锰铁粉2-5重量份、镍粉0.4-0.8重量份、铜粉0.15-0.3重量份、金属铬0.6-0.8重量份、长石粉0.5-0.8重量份、电熔镁砂0.4-0.5重量份和铁粉0.45-1.8重量份。与现有的相比,本发明工艺性能良好,耐大气腐蚀性能好,扩散氢含量低,低温冲击韧性优良。(The invention discloses a Q500qENH coating-free flux-cored wire for bridge steel and a preparation method thereof, wherein the flux-cored wire consists of a steel sheath and a flux core, and the flux core comprises the following components: 3.5 to 5 parts of rutile, 2 to 4 parts of ferrosilicon powder, 0.3 to 0.5 part of ferrotitanium powder, 0.2 to 0.3 part of fluoride, 2 to 5 parts of ferromanganese powder, 0.4 to 0.8 part of nickel powder, 0.15 to 0.3 part of copper powder, 0.6 to 0.8 part of chromium metal, 0.5 to 0.8 part of feldspar powder, 0.4 to 0.5 part of fused magnesia and 0.45 to 1.8 parts of iron powder. Compared with the prior art, the invention has the advantages of good processing performance, good atmospheric corrosion resistance, low content of diffusible hydrogen and excellent low-temperature impact toughness.)

1. A Q500qENH coating-free flux-cored wire for bridge steel consists of a steel sheath and a powder core, wherein the powder core comprises the following components:

rutile 3.5-5 weight portions

2-4 parts of ferrosilicon powder

0.3 to 0.5 weight portion of ferrotitanium powder

0.2 to 0.3 part by weight of fluoride

2-5 parts of ferromanganese powder

0.4-0.8 parts of nickel powder

0.15-0.3 part by weight of copper powder

0.6 to 0.8 weight portion of metallic chromium

0.5 to 0.8 weight portion of feldspar powder

0.4 to 0.5 weight portion of fused magnesia

0.45-1.8 parts by weight of iron powder and

0.10-0.80 parts of rare earth fluoride.

2. The flux-cored welding wire for Q500qENH coating-free bridge steel as claimed in claim 1, wherein the steel sheath comprises the following components: c is more than or equal to 0.01 wt% and less than or equal to 0.05 wt%, Mn is more than or equal to 0.12 wt% and less than or equal to 0.30 wt%, Si is more than 0 and less than or equal to 0.30 wt%, S is more than 0 and less than or equal to 0.010 wt%, P is more than 0 and less than or equal to 0.020 wt%, and the balance is iron powder and inevitable impurities.

3. The Q500qENH paintless flux-cored wire for bridge steel according to claim 2, wherein the steel sheath comprises: 0.025 wt% of C, 0.22 wt% of Mn, 0.02 wt% of Si, 0.008 wt% of S, 0.01 wt% of P, and the balance of iron and inevitable impurities.

4. The flux-cored welding wire for Q500qENH coating-free bridge steel as claimed in any one of claims 1 to 3, wherein: the flux-cored wire comprises a flux-cored wire core and a flux-cored wire core, wherein the flux-cored wire core accounts for 10-20% of the weight of the flux-cored wire.

5. The flux-cored welding wire for Q500qENH coating-free bridge steel as claimed in any one of claims 1 to 3, wherein the steel strip is coated with a flux in a packing ratio of 10-20% and a specification of 1.20-2.40 mm.

6. The flux-cored welding wire for Q500qENH coating-free bridge steel as claimed in any one of claims 1 to 5, wherein: the medicinal skin comprises the following components:

4.2 parts of rutile, 2.0 parts of ferrosilicon powder, 0.5 part of ferrotitanium powder, 0.2 part of fluoride, 5 parts of ferromanganese powder, 0.6 part of nickel powder, 0.15 part of copper powder, 0.6 part of chromium metal, 0.5 part of feldspar, 0.5 part of fused magnesia, 0.45 part of iron powder and 0.3 part of rare earth fluoride; or

3.5 parts of rutile, 2.8 parts of ferrosilicon powder, 0.3 part of ferrotitanium powder, 0.3 part of fluoride, 3 parts of ferromanganese powder, 0.8 part of nickel powder, 0.3 part of copper powder, 0.8 part of feldspar, 0.8 part of metal chromium, 0.4 part of fused magnesia and 0.2 part of iron powder, 1.80 parts of rare earth fluoride; or

4.5 parts of rutile, 4.0 parts of ferrosilicon powder, 0.5 part of ferrotitanium powder, 0.3 part of fluoride, 2 parts of ferromanganese powder, 0.4 part of nickel powder, 0.2 part of copper powder, 0.5 part of feldspar, 0.6 part of chromium metal, 0.4 part of fused magnesia, 1.10 parts of iron powder and 0.5 part of rare earth fluoride.

7. A preparation method of the flux-cored wire for Q500qENH coating-free bridge steel as claimed in any one of claims 1 to 6, which comprises the following steps: mixing the components of the powder core uniformly according to the proportion, placing the steel belt in a welding wire forming machine, injecting the uniformly mixed powder core mixture into a groove of the steel belt which is transversely bent into a U shape, then rolling the steel belt into a wire, and finely drawing the wire to phi 1.20-2.40mm to obtain the steel belt.

8. A welding method of Q500qENH coating-free bridge steel, which adopts the flux-cored wire for Q500qENH coating-free bridge steel of any claim 1 to 6 to weld Q500qENH coating-free steel plates, and the content of diffusible hydrogen of welding cladding metal is less than 5ml/100 g.

Technical Field

The invention relates to the field of welding materials, in particular to a flux-cored welding wire for Q500qENH coating-free bridge steel, a preparation method of the flux-cored welding wire and a welding method.

Background

The railway steel bridge in China is a process of gradual development from 50 years to the present. From the Wuhan Changjiang river bridge, the Jiujiang river bridge, the Wu lake Changjiang river bridge, and the Nanjing Dasheng Guangjiang river bridge, the span of the main bridge span is from 128 meters to 336 meters. The structural form gradually develops to bolt welding and integral node. Particularly, the construction of the great-win Guanchangjiang river bridge in Nanjing enables the railway bridge construction in China to reach the international leading level.

Compared with bridge design and manufacture, the development of domestic bridge steel is earlier, and 16Mnq, 15MnVq and 15MnVNq (standard YB/168-70 and YB (T)10-81 for bridge structural steel) are developed in sixty to eighty years. The 16Mnq is widely applied in the industry, but the use department reflects that the 16Mnq steel plate adopts U-shaped notch impact, and the toughness index is lower. Meanwhile, the thickness effect of the plate is serious, the railway bridge can only be used for 32mm, and the metallurgical quality is difficult to guarantee when the thickness of the plate exceeds the thickness.

At the end of the eighties, due to the construction requirements of the bridges in the Yangtze river, the bridges in the Yangtze river adopt 15MnVNq with sigma s more than or equal to 420Mpa, but the strength is improved by adding vanadium. The steel plate has poor low-temperature toughness and welding performance, which brings great difficulty to bridge manufacture, and the steel grade cannot be popularized and applied after the Jiujiang bridge is manufactured. Bridge steel has become a prominent contradiction that restricts the development of railroad bridges.

In the early nineties, the railway bridge construction faces the construction of a great bridge in the great rivers of the Weuwang lake, the main span reaches 312 meters, and the problem of bridge steel is more prominent. Therefore, the steel 14MnNbq for the large-span railway bridge is jointly developed by the bridge bureau and the Wu steel. The steel adopts an ultra-pure metallurgical method of carbon reduction plus niobium alloy, and has excellent low-temperature impact toughness at-40 ℃ (Akv is more than or equal to 120J at-40 ℃ required by the standard of a turnip lake bridge) on the basis that the yield strength sigma s is more than or equal to 370 MPa. Meanwhile, the welding performance is greatly improved, the problem of plate thickness effect is solved, and 32-50 mm thick steel plates can be supplied in large batches. After the turnip lake bridge is constructed, the 14MnNbq steel can fully meet the requirements of railway bridge construction at that time.

In recent years, with the development of bridge technology, people have higher requirements on bridge durability, and the coating-free steel bridge is produced with such expectations, so that the coating-free steel bridge reduces the maintenance cost of the periodic steel bridge, and particularly, the coating-free steel bridge highlights the advantages of the coating-free steel bridge in regions with serious salt damage near a coastline, plateaus and remote regions. Compared with common steel coating, the coating cost is greatly reduced, the initial cost is saved, the volatile release of organic matters is reduced, and the coating is healthy and environment-friendly. The coating-free weathering steel is formed by adding a proper amount of weathering alloy elements such as Cu, Cr, Ni and the like into common bridge steel, and has the comprehensive function of enabling the surface of a steel structure to form and maintain a compact and stable rust layer under specific treatment and suitable environmental conditions, and preventing rust by rust, thereby having the durable characteristic of long-term atmospheric corrosion resistance.

The coating-free weather-resistant bridge made of the coating-free steel has the advantages that the cost of the whole life cycle is low, the environmental protection significance is important without coating paint, the environmental pollution is reduced, the workload of maintenance and maintenance under severe natural environment in the future of a common steel bridge with coating and the later maintenance cost can be saved, and the practical engineering significance is great. In the countries such as the United states, Japan, Germany and the like, coating-free steel bridges have been popularized in a large amount for a long time, and in recent years, China also speeds up the pace of coating-free steel bridge construction.

With the development trend of high strength and light weight of steel structure materials, Q500qENH weather-resistant steel materials have been successfully developed in several steel mills (sand steel, saddle steel and the like) in China at present, but welding wires matched with Q500qENH weather-resistant steel plates for use cannot be found, and the following defects exist after the existing welding wires are adopted for welding: the flux-cored wire has the advantages that the composition difference is too large, the strength is not matched, the-40 ℃ low-temperature impact toughness does not reach the standard, for example, CN 101804529A discloses the flux-cored wire of the weathering steel, the normal-temperature impact toughness of the flux-cored wire is better, but the-40 ℃ low-temperature impact toughness of the flux-cored wire is poor, and the flux-cored wire can not be used for welding the low-temperature steel.

Disclosure of Invention

In view of the above-mentioned drawbacks, and in order to develop a welding material compatible with Q500qENH coating-free steel, the atlantic, sichuan, university, sichuan, inc established a special group to develop such a coating-free steel-compatible welding material. On one hand, the successful implementation of the invention provides guarantee for the welding matched with the coating-free steel, and improves the technical capability and level of domestic welding material enterprises; on the other hand, for bridge manufacturing enterprises, the maintenance cost is reduced, and the problem of environmental pollution caused by paint is avoided. Therefore, the implementation of the invention has obvious economic and social benefits and great strategic significance.

The invention provides a high-toughness Q500qENH gas-shielded flux-cored wire for coating-free bridge steel, which has good welding technological performance and physical and chemical properties. The purposes of stable electric arc, small splashing, attractive weld forming and the like are achieved on the welding process performance; the performance of the material achieves the purposes of good mechanical property and atmospheric corrosion resistance.

The technical scheme is as follows: a Q500qENH coating-free flux-cored wire for bridge steel consists of a steel sheath and a powder core, wherein the powder core comprises the following components:

rutile 3.5-5 weight portions

2-4 parts of ferrosilicon powder

0.3 to 0.5 weight portion of ferrotitanium powder

0.2 to 0.3 part by weight of fluoride

2-5 parts of ferromanganese powder

0.4-0.8 parts of nickel powder

0.15-0.3 part by weight of copper powder

0.6 to 0.8 weight portion of metallic chromium

0.5 to 0.8 weight portion of feldspar powder

0.4 to 0.5 weight portion of fused magnesia

0.45-1.8 parts by weight of iron powder and

0.10-0.80 parts of rare earth fluoride.

Preferably, the steel outer skin comprises the following components: c is more than or equal to 0.01 wt% and less than or equal to 0.05 wt%, Mn is more than or equal to 0.12 wt% and less than or equal to 0.30 wt%, Si is more than 0 and less than or equal to 0.30 wt%, S is more than 0 and less than or equal to 0.010 wt%, P is more than 0 and less than or equal to 0.020 wt%, and the balance is iron powder and inevitable impurities.

Preferably, the steel outer skin comprises the following components: 0.025 wt% of C, 0.22 wt% of Mn, 0.02 wt% of Si, 0.008 wt% of S, 0.01 wt% of P, and the balance of iron and inevitable impurities.

Preferably, the flux-cored wire comprises 10-20% of the flux-cored wire by weight.

Preferably, the steel strip is wrapped to ensure that the filling rate of the medicinal powder is 10-20% and the specification is 1.20-2.40 mm.

Preferably, the components of the coating are as follows:

4.2 parts of rutile, 2.0 parts of ferrosilicon powder, 0.5 part of ferrotitanium powder, 0.2 part of fluoride, 5 parts of ferromanganese powder, 0.6 part of nickel powder, 0.15 part of copper powder, 0.6 part of chromium metal, 0.5 part of feldspar, 0.5 part of fused magnesia, 0.45 part of iron powder and 0.3 part of rare earth fluoride; or

3.5 parts of rutile, 2.8 parts of ferrosilicon powder, 0.3 part of ferrotitanium powder, 0.3 part of fluoride, 3 parts of ferromanganese powder, 0.8 part of nickel powder, 0.3 part of copper powder, 0.8 part of feldspar, 0.8 part of metal chromium, 0.4 part of fused magnesia and 0.2 part of iron powder, 1.80 parts of rare earth fluoride; or

4.5 parts of rutile, 4.0 parts of ferrosilicon powder, 0.5 part of ferrotitanium powder, 0.3 part of fluoride, 2 parts of ferromanganese powder, 0.4 part of nickel powder, 0.2 part of copper powder, 0.5 part of feldspar, 0.6 part of chromium metal, 0.4 part of fused magnesia, 1.10 parts of iron powder and 0.5 part of rare earth fluoride.

Preferably, the fluoride is one or more of calcium fluoride, potassium fluotitanate, potassium fluoroaluminate and the like.

The invention also provides a preparation method of the gas-shielded flux-cored wire for the high-toughness and atmospheric corrosion-resistant Q500qENH coating-free bridge steel.

The technical scheme is as follows: a preparation method of a high-toughness and atmospheric corrosion-resistant Q500qENH coating-free bridge steel gas-shielded flux-cored wire comprises the following steps:

mixing the components of the powder core uniformly according to the proportion, placing the steel belt in a welding wire forming machine, injecting the uniformly mixed powder core mixture into a groove of the steel belt which is transversely bent into a U shape, then rolling the steel belt into a wire, and finely drawing the wire to phi 1.20-2.40mm to obtain the steel belt.

The invention also provides a welding method of the gas-shielded flux-cored wire for the high-toughness and atmospheric corrosion-resistant Q500qENH coating-free bridge steel.

The technical scheme is as follows: the welding method of the gas-shielded flux-cored wire for the high-toughness and atmospheric corrosion-resistant Q500qENH coating-free bridge steel is characterized in that the Q500qENH coating-free steel plate is welded by the gas-shielded flux-cored wire for the high-toughness and atmospheric corrosion-resistant Q500qENH coating-free bridge steel, and the content of diffusible hydrogen of welding clad metal is less than 5ml/100 g.

The invention principle is as follows:

silicon iron: silicon is an important deoxidizer and is also an important alloying agent of the weld metal, and the addition of silicon in the weld can increase the quantity of acicular ferrite in the weld metal, reduce the oxygen content of the weld metal and improve the impact toughness of the weld metal, but the contrary is true when the silicon is too high; the silicon-manganese combined deoxidation method has a good effect.

Rutile: the main chemical component is titanium oxide (TiO2) which is mainly used as an arc stabilizer and a slag former to ensure stable electric arc and fine forming of a welding line.

Nickel: the nickel is used as an inoculant to refine grains, reduce segregation and promote the formation of acicular ferrite, thereby improving the toughness of the ferrite. The nickel also increases dislocation energy, promotes the screw dislocation cross slip at low temperature, increases the work consumed by crack propagation, and also improves the toughness. Ni has corrosion resistance effect together with Cr and Cu substances. Mainly from metallic nickel.

Fluoride: fluorine is used for reducing the content of diffused hydrogen in deposited metal, but the content of fluoride is too high, so that electric arc is unstable during welding, splashing is increased, and electric arc sound is deteriorated, and the fluoride mainly comes from sodium fluoride, sodium fluosilicate, potassium fluosilicate or ice crystal powder.

Copper powder: the addition of copper powder to the flux core can improve the atmospheric corrosion resistance of the deposited metal.

Has the advantages that:

through the organic combination of the components, the welding wire deposits metal after welding: the tensile strength is more than or equal to 620Mpa, the yield strength is more than or equal to 500Mpa, the elongation is more than or equal to 17 percent, the impact reaches 100J at the temperature of 40 ℃, and the diffusible hydrogen content of deposited metal is less than 5ml/100 g. Effectively improves the overall performance of the welding seam, and solves the problems of insufficient low-temperature toughness and atmospheric corrosion resistance of the welding seam metal. The welding process has good performance, stable electric arc, small splashing and beautiful welding line formation.

Detailed Description

The present invention will be further described with reference to the following examples.